PROJECT SUMMARY The proposed Phase II continuation of the Model Organism Screening Center (MOSC) for the Undiagnosed Diseases Network (UDN) builds on extensive tools, reagents, and pipelines that we established in Phase I. The leadership team represents international expertise in Drosophila, zebrafish, and human medical genetics. In Phase I, the MOSC developed an interface in the UDN Gateway that supports submission of cases, genes, and variants that the clinical sites propose for model organism studies. The MOSC also developed MARRVEL (www.MARRVEL.org), an online tool that integrates human and model organism data and helps to prioritize variants. The MOSC further established collaborations with independently funded collections of rare disease cohorts at Baylor College of Medicine (BCM) that we use to identify matches to UDN phenotypes and genetic variants. The MOSC holds regular conference calls with clinical sites and provides tools that help them to select variants. The MOSC will continue calls with the sites to review informatic analyses and then assign variants (estimated at 45 per year) for in-depth model organism studies of variants and genes. In the Drosophila Core at BCM, approximately 30 genes and variants per year are studied with innovative technology in flies. For 15 additional genes/variants that affect vertebrate-specific genes or biology, the Zebrafish Core at the University of Oregon will induce new mutations in zebrafish with CRISPR/Cas9 followed by high throughput phenotypic analyses. The MOSC will also develop tools and reagents for future variant studies in Drosophila and zebrafish for an additional 100 genes per year. We will share these additional resources with the broader research community through an innovative ModelMatcher service and will also prioritize genes for generation of mouse knock-outs in collaboration with the Knockout Mouse Phenotyping Project (KOMP). Thus, the proposed center will provide informatics selection, human genetics expertise, broad versatile model organism resources, and in-depth studies of UDN cases to aid in diagnosis. The MOSC employs the most innovative technologies in human genomics and Drosophila and zebrafish genetics, based on extensive previous experience modeling human disease.